Bad caliper?

[Docmallory]

Vehicle - '97 LC 120K miles, fairly new to me

Preparing for the upcoming birf job, so I thought I'd assess the front brakes beforehand.

Passenger side front - both pads are evenly worn and have probably half of the original thickness left.

Driver side - inboard pad is well worn, almost down to the squealer bar. This pad is worn evenly. Outboard pad is worn unevenly, with slightly greater thickness at the front end than the back end. Overall, the outboard pad, while uneven, is not nearly as worn as the inboard pad. The outbard DS pad is almost as thick as the PS pads.

Both front rotors are moderately scored and would need to be turned or replaced for new pads.

Haven't checked the rear brakes yet. Braking is fine, with no pulls or anything. There is a very slight undulation (a la warped rotor) that is not felt in the steering wheel (so I'm thinking it's the rear brakes).

[glow=red,2,300]So, what's your diagnosis and advice? [/glow]

I have new front rotors and 100 series pads on order, and I'm guessing I'll need to order a DS caliper as well.

 

[landtank]

Unless you can find some debris in the mechanicals to account for some binding, I'd say the caliper is sticking. I haven't rebuilt one an 80 but kits are available. I'm pretty sure some on here have done it and remarked that it wasn't that hard.

 

[scottm]

I'm in the same boat with my wife's truck. One front, left pad wore unevenly, the other wore evenly, the pads on the other front wheel wore much less. All four pistons on both front wheels extend and retract smoothly. I've got new 100 pads in there now, with a new rotor just arrived. Unfortunately I'm travelling and we're having my daughter's open house this week, no projects allowed. A mechanic I work with suggested my flex hoses may be deteriorating, chunks may be getting in and plugging things, possibly causing pressure to not leave the caliper after braking and causing drag. I'll slap it all together and monitor the pads carefully.

 

[xl715]

Try lubing the slide pins on the calipers. If these bind up they cause a caliper to wear one side of the pads and not the other. This is a lot more common than debris from the lines.

 

[IdahoDoug]

Agree on the slide pins. Scott's sound like slight sticking, which happens when the caliper pistons get a ring of grundge that causes them to hang up on the rubber seal they ride in and out of. Using the force of pliers or such easily overcomes this and retracts them, so you really would have to be familiar with them to detect that but in operation the pistons will hang a bit. If you want to try something short of a rebuild, try extending the pistons quite a bit while the pads are out. Wipe the piston and look for the build up. Push em back in and consider bleeding them to remove whatever you've scraped off the piston inside the seal by extending them that's now in the caliper fluid. This would only take a few pumps per caliper.

I rebuilt my fronts a while ago after noting uneven but uniform wear. Was around $22 for the rebuild kit from my Dealer that handled both front calipers. Took some time - couple hours added to a normal pad replacement - but a 3 banana job only due to some difficulty in getting the pistons out (I don't have air and had to use pedal pressure, etc). Do a search for "caliper" and "rebuild" in the text body and my username.

The uneven wear is a strong indicator of a hanging piston and the end result will be the angled brake pad backing plate causing one piston to jam as they're getting some lateral force. I hear those are ugly to free and often require a new caliper piston.

I've had luck with the "extend/clean/bleed a bit" routine on other cars, but decided not to do it here only because we tow heavy. Trucky no stoppy with 3 tons of boat means really bad stuff can happen, eh?

DougM

 

[landtank]

What I would call slide pins are on the rear but not the front.

 

[scottm]

I replaced my slide pin boots often on my Audi, cheap insurance, how long do they last on these trucks?

 

[landtank]

I've always used white lithium. Stay away from the anti seize stuff as it will dry out and actually bind some.